Detailed Explanation for this Vulnerability Test
The remote host is affected by the vulnerability described in GLSA-200608-05
(LibVNCServer: Authentication bypass)

LibVNCServer fails to properly validate protocol types effectively
letting users decide what protocol to use, such as "Type 1 - None".
LibVNCServer will accept this security type, even if it is not offered
by the server.

Impact

A possible hacker could use this vulnerability to gain unauthorized access
with the rights of the user running the VNC server.